Atomistic Simulation of Defect Energy in Pyrochlores and its Effect on Disorder

Abstract:

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To enhance the high-temperature stability of zirconate pyrochlore structures, one has to focus
on their transformation to the disordered state, fluorite. An atomistic simulation calculation is presented
in this paper to predict the propensity of rare earth zirconate pyrochlores to transform to fluorite at high
temperature. By detailed calculation of defect formation energy of cation antisites and Frenkel pair, as
well as their interactions, the mechanisms of disorder transformation are ascertained. The results show
that the tendency of cation disorder is less than the anion’s and disorder transformation will accelerate in
advanced stage. The calculation of defect energy in pyrozirconates with different cation on the A site have
proved helpful in unraveling their different order-disorder transformation tendency.

Abstract: The results of the studies on complex oxide systems based on antimony oxide are presented with the aim to isolate strontium from radioactive wastes solutions. The compositions for experimental investigations are selected by computational screening of potentially suitable mixed oxide systems using atomistic modeling. Based on the results of experimental studies of selected compositions, methods for isolating strontium are proposed for various solutions and conditions of disposal.